Piezoelectric transducers, in general, convert electrical signals into mechanical vibrations or vice versa. Piezoelectric transducers typically utilize a piezoelectric film where electrical signals or mechanical vibrations induce a morphological change of the piezoelectric film (i.e., due to voltage application or due to a pressure applied to the piezoelectric film). Piezoelectric transducers are generally used to actuate/sense different frequencies. Piezoelectric transducers may operate as a resonator to provide a maximum response when operated at its resonant frequency.
One typical piezoelectric transducer includes a surface acoustic wave (SAW) transducer that, when excited, produces mechanical vibrations along the surface of the piezoelectric film. SAW piezoelectric transducers typically do not scale well to radio frequency (RF) applications due to a need for submicrometer lithography and decreasing power handling capabilities. Another type of piezoelectric transducer includes a contour-mode piezoelectric transducer that, when excited, produces mechanical vibrations throughout the piezoelectric film and where the fundamental frequency is defined by the in-planed dimensions of the piezoelectric film.
In general, there is a need for RF-capable piezoelectric transducers which are small in size, energy efficient, capable of complementary metal oxide semiconductor (CMOS) integration, capable of sensing/actuating at high frequencies and that are inexpensive.